Method and device for synthesizing high orientationally arranged carbon nano-tube by using organic liquid

ABSTRACT

A method capable of synthesizing carbon nanotubes at low cost and large quantities, an apparatus usable for carrying out the method, and carbon nanotubes densely aligned on and firmly bonded to a Si substrate over, and oriented perpendicular to, an entire surface thereof are provided. Highly oriented, aligned carbon nanotubes are synthesized from an organic liquid by forming a substrate with a buildup thereon of a thin film or fine insular particles composed of at least one metallic element; exposing the substrate ( 3 ) having the buildup to a hydrogen plasma; and heating the substrate ( 3 ) exposed to the hydrogen plasma in the organic liquid ( 10 ) to a predetermined temperature. The synthesis apparatus comprises: a liquid chamber or tank ( 1 ) for an organic liquid; a water cooling means ( 2 ) for cooling the liquid tank ( 1 ) from its outside; a substrate holder ( 5 ) for holding a substrate ( 3 ), the holder having electrodes ( 4 ) for passing an electric current through the substrate ( 3 ); a condensing means ( 7 ) comprising water cooling tubes ( 6 ) for cooling and condensing vapor made from the organic liquid by its vaporization to return it to the liquid for return into the liquid tank ( 1 ); a valve ( 8 ) through which N 2  gas is introduced; and a lid ( 9 ) that carries the substrate holder ( 5 ), the condensing means ( 7 ) and the valve ( 8 ). The organic liquid ( 10 ) is thus tightly sealed in the liquid tank ( 1 ) by the lid ( 9 ). This synthesis apparatus allows carbon nanotubes to be synthesized in large quantities, at low cost and in safety. Highly coaxially and densely oriented, aligned carbon nanotubes can be synthesized in the form of a bundle thereof, which when used in a variety of products brings about various excellent effects including extremely high usability.

TECHNICAL FIELD

[0001] The present invention relates to a method of synthesizing alignedand oriented carbon nanotubes from an organic liquid and an apparatusfor use in carrying out the method as well as carbon nanotubes made bythe method.

BACKGROUND ART

[0002] Carbon nanotubes, which possess unique electrical and mechanicalproperties, have a high potential applicability to the futurenanotechnologies such as field emission electron sources, nanoscaleelectronic devices, chemical storage systems, and mechanicalreinforcement materials.

[0003] Since carbon nanotubes was discovered in a cathodic depositproduced with an electric discharge brought about using a carbonelectrode in a fullerene forming apparatus, a variety of techniques havebeen proposed for synthesizing carbon nanotubes. These synthesistechniques aim to be able to produce carbon nanotube in large quantitiesand also to synthesize carbon nanotubes having a specific function. Suchspecific functions are, among others, the function to suspend thecatalytic ability for a hydrocarbon, the function to electrolyze acondensate phase and the catalytic function for SiC sublimation. Suchcarbon nanotubes must have an oriented growth structure that agrees withsuch a particular function.

[0004] The synthesis methods so far proposed have been found, however,to be capable of producing carbon nanotubes only at a yield just enoughfor them to be used in research and far less than the methods can beapplied to their industrial production. Another problem with these priormethods is that the nanotubes aligned thereby on a substrate are week intheir bonding strength with the substrate and are thus hard to handle.

[0005] It would be advantageous if carbon nanotubes can be synthesizedin large quantities and at a low cost using the most updated Sitechnology, for example, by the use of a material and equipment employedin the Si semiconductor process. Then, it will be possible to supply atlow cost and in bulk nanotechnology products which with the best use ofthe unique properties of carbon nanotubes are functionally excellent.

DISCLOSURE OF THE INVENTION

[0006] With the aforementioned prior-art problems taken into account,the present invention has for its objects to provide a synthesis methodthat allows a carbon nanotube or nanotubes to be produced at a low costand large quantities and an apparatus for use in carrying out the methodas well as carbon nanotubes made by the method, the carbon nanotube ornanotubes being firmly bonded to a substrate as highly oriented anddensely aligned thereon.

[0007] In order to achieve the first of the objects mentioned above,there is provided in accordance with the present invention a method ofsynthesizing highly oriented, aligned carbon nanotubes from an organicliquid, characterized in that it comprises the steps of: forming asubstrate with a buildup thereon of a thin film or fine insularparticles composed of at least one metallic element; exposing the saidsubstrate having the said buildup to a hydrogen plasma; and heating thesaid substrate exposed to the hydrogen plasma in an organic liquid to apredetermined temperature whereby highly oriented, aligned carbonnanotubes are synthesized.

[0008] The said substrate is preferably a Si substrate.

[0009] The said at least one metallic element of which the said buildupis composed is preferably one or more elements selected from the groupwhich consists of Fe, Co and Ni.

[0010] The organic liquid may be alcohol, e. g., methanol or ethanol.The Si substrate may be heated to a predetermined temperature by passingan electric current therethrough.

[0011] According to this method, exposing to a high-temperature hydrogenplasma a Si substrate formed thereon with either a thin Fe film or fineinsular particles composed of, e. g., Fe element, will cause either thethin Fe film to become fine particles of nanometers in size distributedinsularly on the Si substrate and firmly bonded thereto, or the fineinsular particles to be firmly bonded to the Si substrate, therebyforming fine Fe liquid particles. Then, heating the Si substrate to ahigh temperature by passing an electric current therethrough will causethe organic liquid in the vicinity of the Si substrate to be decomposedby a catalytic reaction in a thermal non-equilibrium state to formcarbon atoms and then lead to the supersaturated solution of such formedcarbon atoms into those fine Fe liquid particles. Then, the sharptemperature gradient between the high-temperature Si substrate surfaceand the organic liquid adjacent thereto will cause the carbon atoms inthe fine Fe liquid particles to be precipitated on their surfaces,thereby forming growth nuclei. With these growth nuclei continuouslysupplied with carbon atoms from the fine Fe liquid particles, carbonnanotubes grow in a direction perpendicular to the Si substrate surface.

[0012] This method, which permits using a raw material and equipmentcommonly used in the conventional semiconductor process, allows low-costproduction. Also, the method whereby nanotubes are grown concurrentlyover an entire Si substrate surface allows their mass production.Further, the method wherein the Si substrate need not be of singlecrystal makes the substrate of low-cost material.

[0013] Furthermore, by this method which permits a choice among avariety of types of the organic liquid, so-called doped nanotubes can besynthesized, which contain an element or elements other than carbon.

[0014] There is also provided in accordance with the present inventionan apparatus for synthesizing highly oriented, aligned carbon nanotubes,characterized in that it comprises: a liquid tank for retaining anorganic liquid; a cooling means for cooling the said organic liquid soas to maintain it at a temperature lower than a boiling point thereof; acondensing means for condensing the said organic liquid becoming gaseousin phase into its original liquid phase and returning the same into thesaid liquid tank; a substrate holding means having an electrode meansfor passing an electric current through the said substrate in the saidorganic liquid; an inert gas inlet means for removing air from the saidapparatus; and a tank sealing means for sealing the said liquid tank toprevent the said organic liquid becoming gaseous in phase from flyingoff.

[0015] This apparatus makeup allows an organic liquid to be held at atemperature lower than its boiling point and the substrate at a highgrowth-temperature and enables highly oriented, aligned carbon nanotubesto be synthesized.

[0016] Also, the apparatus whereby a gasified portion of the organicliquid is condensed and returned to its original liquid phase has nowasteful consumption of the organic liquid as the raw material. Further,there may be no risk of the gasified liquid organic mixing with air andthen causing an explosion or burning.

[0017] Also, having the means for introducing the inert gas furthereliminates the risk of the gasified liquid organic mixing with air andthen causing an explosion or burning in the liquid tank.

[0018] There is also provided in accordance with the present inventionhighly oriented, aligned carbon nanotubes, characterized in that suchcarbon nanotubes are densely aligned on and firmly bonded to a Sisubstrate over, and oriented perpendicular to, an entire surfacethereof.

[0019] There is also provided in accordance with the present inventionhighly oriented, aligned carbon nanotubes, characterized in that suchcarbon nanotubes are coaxially oriented, equal in length, and fastenedtogether.

[0020] So constructed as mentioned above, the carbon nanotubes which aredensely aligned on and firmly bonded to a Si substrate over, andoriented perpendicular to, an entire surface thereof are readilymachinable into, e. g., a device.

[0021] The carbon nanotubes which are coaxially oriented, equal inlength, and fastened together are readily machinable into, e. g., adevice.

[0022] According to the present invention, carbon nanotubes can besynthesized at low cost. Accordingly, many nanotechnology products whichmake the best use of unique properties of carbon nanotubes can beproduced at low cost and in large quantities.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will better be understood from thefollowing detailed description and the drawings attached hereto showingcertain illustrative forms of embodiment of the present invention. Inthis connection, it should be noted that such forms of embodimentillustrated in the accompanying drawings hereof are intended in no wayto limit the present invention but to facilitate an explanation andunderstanding thereof. In the drawings:

[0024]FIG. 1 is a diagram illustrating the makeup of an apparatus forsynthesizing highly oriented, aligned carbon nanotubes from an organicliquid in accordance with the present invention;

[0025]FIG. 2 is a diagram illustrating a growth mechanism of carbonnanotubes synthesized using an organic liquid in accordance with thepresent invention;

[0026]FIG. 3 shows images by SEM (Scanning Electron Microscope) of thecarbon nanotubes synthesized;

[0027]FIG. 4 shows images by HRTEM (High Resolution TransmissionElectron Microscope) of the synthesized carbon nanotube;

[0028]FIG. 5 shows further images by HRTEM of the synthesized carbonnanotube;

[0029]FIG. 6 shows an image by HRTEM of a carbon nanotube grown on a Sisubstrate in ethanol; and

[0030]FIG. 7 shows SEM images of carbon nanotubes synthesized withouthaving the hydrogen plasma treatment.

BEST MODES FOR CARRYING OUT THE INVENTION

[0031] Hereinafter, the present invention will be described in detailwith reference to suitable forms of implementation thereof illustratedin the drawing figures.

[0032] At the outset, mention is made of an apparatus aspect of thesynthesis of a highly oriented, aligned carbon nanotube or nanotubesfrom an organic liquid in accordance with the present invention.

[0033]FIG. 1 is a diagram illustrating the makeup of an apparatus forsynthesizing highly oriented, aligned carbon nanotubes from an organicliquid in accordance with the present invention. The synthesis apparatusincludes a liquid chamber or tank 1 for an organic liquid; a watercooling means 2 for cooling the liquid tank 1 from its outside; asubstrate holder 5 for holding a substrate 3, the holder havingelectrodes 4 for passing an electric current through the substrate 3; acondensing means 7 comprising a plurality of water cooling tubes 6 forcooling and condensing vapor made from the organic liquid 10 by itsvaporization to return the vapor to the liquid for return into theliquid tank 1; a valve 8 for introducing N₂ gas; and a lid 9 thatcarries the substrate holder 5, the condensing means 7 and the valve 8.The organic liquid 10 is thus tightly sealed in the liquid tank 1 by thelid 9.

[0034] In order to permit carbon nanotubes to be synthesized from theorganic liquid, this apparatus is designed to maintain the organicliquid at a temperature lower than its boiling point and the substrateat a high growth temperature. Also, a vaporized or gasified portion ofthe organic liquid is returned upon condensation so that there can be nowasteful consumption of the organic liquid as the raw material andfurther so that there may be no risk of the gasified liquid organicmixing with air and then causing an explosion or burning. Also, havingthe means for introducing the inert gas further eliminates the risk ofthe gasified liquid organic mixing with air and then causing anexplosion or burning in the liquid tank.

[0035] Mention is next made of a method of synthesizing highly oriented,aligned carbon nanotubes from an organic liquid in accordance with thepresent invention and using the synthesis apparatus shown in FIG. 1. Anexample is here taken in which the substrate is composed of Si, themetallic thin film is a Fe thin film, the organic liquid is methanol.

[0036] The Si substrate, which is electrically conductive, is washed andcleaned, a Fe thin film is built up thereon, e. g., by sputtering in anargon atmosphere, to a film thickness that is selected to meet with aparticular purpose to be achieved since the film thickness determinesthe diameter and density of nanotubes being synthesized.

[0037] The Si substrate having the Fe thin film built up thereon isexposed to a hydrogen plasma and heated at a temperature of 850° C. Thisplasma treatment makes the Fe thin film become fine liquid particleswhich are distributed insularly over the Si substrate and firmly bondedthereto. The exposure with the hydrogen plasma also makes the fineliquid particles uniform in their diameter and distribution.

[0038] The Si substrate exposed to the hydrogen plasma is disposed onthe substrate holder 5 in the synthesis apparatus of FIG. 1, which isthen supplied with methanol 10 and thereafter has N₂ gas introducedthrough the valve 8 to replace the residual air in the synthesisapparatus therewith.

[0039] Next, an electric current is passed through the Si substratebetween the electrodes 4 to heat the Si substrate. The electric currentis selected in magnitude such that the Si substrate has a temperature of930° C., and this selected current magnitude is maintained during thesynthesis. Bubbles made of methanol gas are produced from the surface ofthe Si substrate, which is covered with these bubbles. Here, it isnecessary that the methanol 10 be maintained at a temperature lower thanits boiling point, and to this end it is cooled using the water coolingmeans 2. Also, a gasified portion of the methanol liquid is returned bythe condensing means 7 to the liquid phase which is returned to theliquid tank 1.

[0040] The synthesis apparatus is held in the state mentioned above fora given time period in which the carbon nanotubes being synthesized growto a desired length.

[0041] The growth mechanism of the carbon nanotubes synthesized inaccordance with the present invention is considered as mentioned below.An example is here again taken in which the substrate is composed of Si,the metallic thin film is a Fe thin film and the organic liquid ismethanol.

[0042]FIG. 2 is a diagram illustrating a growth mechanism of carbonnanotubes synthesized using an organic liquid in accordance with thepresent invention. In the Figure, the surface of the Si substrate 3 isheld at an elevated temperature of about 900° C. while the methanolliquid adjacent to the surface of the Si substrate 3 is held at atemperature of about 60° C. Also, the surface of the Si substrate 3 iscovered with methanol gas 21, and there exists a sharp temperaturegradient from the Si substrate surface towards the liquid. It isconsidered that this sharp temperature gradient coupled with thecatalytic action of Fe brings about a unique pyrolytic reaction in themethanol gas 21, which in turn generates carbon atoms that penetrateinto the fine Fe liquid particles 22. To wit, the catalytic reaction ofFe in a thermal non-equilibrium state generates carbon atoms.

[0043] The generated carbon atoms penetrate into a fine Fe liquidparticle 22 which is supersaturated therewith. The temperature gradientacross the Si substrate surface causes the carbon atoms in the fine Feliquid particle 22 to be precipitated on a surface thereof, therebyforming a growth nucleus thereon, which is then continuously suppliedwith carbon atoms from the fine Fe liquid particle 22 with the resultthat a carbon nanotube 23 grows on the nucleus.

[0044] Example 1 is next shown.

[0045] In this Example, use was made of high-purity (99.7%) methanol forthe organic liquid. Also used was a (100) face-oriented Si substratehaving a low resistivity of 0.002 Ω·cm and being 10×20×1 mm³ in size.The Si substrate was washed and cleaned, first supersonically in acetoneand then by etching with a 3% hydrofluoric acid (hydrogen fluoride)solution.

[0046] The (100) Si substrate had a Fe thin film of 25 nm thick built upthereon by sputtering in Ar gas and thereafter was subjected to thein-hydrogen plasma treatment at a substrate temperature of 850° C. for atime period of 20 minutes to increase the adhesive strength of the Fethin film to the substrate and to form fine Fe particles in order toform nuclei for the growth of carbon nanotubes.

[0047] This Si substrate was disposed on the substrate holder 3 of FIG.1 and heated to a temperature of 930° C. by passing a direct currenttherethrough. A large number of bubbles were formed, rising to themethanol liquid surface, and the Si substrate surface was covered withthese bubbles. The temperature of the methanol liquid in the liquid tank1 rose to about 60° C. The cooling means 2 was needed to maintain themethanol liquid at a temperature lower than its boiling point and so wasthe condensing means 7 to recover a vaporized portion of the methanolliquid. The Si substrate temperature was measured using an opticalradiation thermometer with its focal point focused on a substratesurface area whose temperature was to be measured. The electric currentpassed through the Si substrate was maintained in magnitude during thegrowth. It was observed that the substrate temperature decreased gentlyas the carbon nanotubes became longer in length.

[0048]FIG. 3 shows images by SEM (Scanning Electron Microscope) of thecarbon nanotubes synthesized. FIG. 3(a) shows an SEM image taken fromobliquely above of carbon nanotubes in a plane of cleavage. Seen flat inthe upper part of the Figure indicates the upper surface of the carbonnanotubes and seen striped or fibrous in the lower part of the Figureindicates side faces of the carbon nanotubes grown densely andperpendicular to the Si substrate. From the Figure, it is clearly seenthat the carbon nanotubes which are coaxial and equal in length havegrown perpendicular to the Si substrate and densely over the entire Sisubstrate surface.

[0049]FIG. 3(b) shows an SEM image of the carbon nanotubes stripped offfrom the Si substrate. From the Figure it is seen that stripped off fromthe Si substrate, the carbon nanotubes which are coaxial and equal inlength lie in the state that they stick to one another to form a bundlethereof. Also, the ends of the carbon nanotubes draw together to form aflat profile. With the naked eye, it is seen as if it is a black lump.The carbon nanotubes on the Si substrate never came off without anexternal force applied to them, e. g., unless they are scratched withsomething hard.

[0050] The axial growth rate of the carbon nanotubes increased as thesubstrate temperature was increased. The nanotubes grew longerlengthwise with time. With the EDX (Energy Dispersive X-ray) deviceattached to the SEM unit, it was confirmed that the carbon nanotubeswere chemically composed of carbon alone. It is clearly seen from theFigure that a bundle of carbon nanotubes which are highly dense andcoaxially oriented is obtained according to the synthetic method of thepresent invention.

[0051]FIG. 4 shows images by HRTEM (High Resolution TransmissionElectron Microscope) of the synthesized carbon nanotube. As is apparentfrom FIG. 4, the carbon nanotube is basically gentle, uniform, hollow,and multi-layered. The multi-layered nanotube had its layers spacedapart from one another by a distance of 0.34 nm. The carbon nanotubesfor the most part are uniform, and some of them are somewhat irregular,in radius over their length. The carbon nanotubes had their outerdiameters ranging and distributed between 13 and 26 nm with 20 nm as thecenter of distribution. The carbon nanotubes had a ratio of their radiusto wall or shell thickness ranging from about 1.2 to 2.1. Some latticemismatches and defects were found in the edge and surface areas of thetube walls. This is considered to be due to radical oxygen atomsproduced by uneven catalytic reactions on the Si substrate surface.

[0052]FIG. 5 shows further images by HRTEM of the synthesized carbonnanotube. As is seen from the Figure, the tip of the carbon nanotube isclosed with an almost one-piece cap. Seen as a black spot in the Figurehas been confirmed to be Fe. And as such, Fe on the Si substrate wasdetected in a region of the tip of each of a few carbon nanotubes. Thecarbon nanotubes have their roots resting on the substrate surface, eachin the form of an open tube.

[0053] Next, Example 2 is shown.

[0054] In this Example, too, the same synthesis conditions as in Example1 were adopted except the use of different temperatures and of ethanolinstead of methanol to be able to form carbon nanotubes. A Si substratewas heated to a temperature of 860° C. in an ethanol liquid which washeld at a temperature of 70° C.

[0055]FIG. 6 shows an image by HRTEM of a carbon nanotube then grown onthe Si substrate in the ethanol liquid held at 70° C. As is apparentfrom FIG. 6, the carbon nanotube then formed is a nearly hollow andmulti-layered carbon nanotube. The carbon nanotubes had a ratio of theirradius to tube shell thickness ranging from 2.2 to 5.8. The carbonnanotubes as those in Example 1 had their tips each closed with analmost one-piece cap.

[0056] Next, an example is shown which substantiates the catalyticfunction of a Fe thin film.

[0057] Namely, using a Si substrate not formed with the Fe thin film,Example 1 was carried out to make a synthesis from methanol, but failedto grow carbon nanotubes as in the Example. This result demonstrates thecatalytic role of Fe.

[0058] Next, an example is shown which substantiates the effectivenessof the in-hydrogen plasma treatment.

[0059] Namely, Example 1 was carried out in methanol for a Si substrateformed with a Fe thin film but not subjected to the in-hydrogen plasmatreatment.

[0060]FIG. 7 shows SEM images of carbon nanotubes synthesized withouthaving the in-hydrogen plasma treatment. As is apparent from the Figure,the carbon nanotubes synthesized with the Si substrate formed with a Fethin film but not subjected to the in-hydrogen plasma treatment wereirregular in arrangement and widespread in diameter. It is seen that allthe carbon nanotubes lie while being curved in various ways on thesubstrate, some of which stick to one another to make something likebeams. From this, it is seen that the in-hydrogen plasma treatment iseffective to synthesize carbon nanotubes which are uniform in system andgrow perpendicular to the Si substrate.

[0061] Methanol and ethanol are each one of the most common organicliquids. They are colorless liquids having their respective boilingpoints of 64.96° C. and 78.5° C. When contacted with air, they mayexplode or burn into almost colorless flame. The safety of an organicliquid is assured, however, if the high-temperature substrate isimmersed therein and thus prevented from contacting with the atmosphere.In this system designed by the present inventors, use is made of a watercoolant for the heated organic liquid and of condensing a gasifiedportion thereof to maintain the organic liquid at a temperature lowerthan its boiling point. The safety is thereby made all the more certain.

[0062] In the forms of implementation illustrated, mention was made onlyof methanol and ethanol for the organic liquid. It will be obvious,however, that the use of other selected types of organic liquids allowsmaking carbon nanotubes of various types and nanotubes composed of orcontaining another or other elements than carbon.

[0063] It should be noted that a method of synthesizing a highlyoriented, aligned carbon nanotube or nanotubes from an organic liquid inaccordance with the present invention involves several importantfeatures.

[0064] First, a carbon nanotube is formed by a catalytic reaction in athermal non-equilibrium state. Also, the end of growth of a carbonnanotube is its root portion on a substrate surface where thetemperature in the organic liquid can be controlled.

[0065] Second, the liquid surrounding the substrate allows a largetemperature gradient to be created in a direction perpendicular to thesubstrate surface which is the root portion of a carbon nanotube. Thislarge temperature gradient is considered to be an important generativepower for the growth of a carbon nanotube in a direction perpendicularto the substrate surface.

[0066] Third, the method of synthesis according to the present inventionis extremely simple, yet allowing highly (coaxially) oriented, alignedcarbon nanotube to be formed over a large area. Also, introducinganother element or other elements into the source liquid allows a carbonnanotube or nanotubes doped with the element or elements to besynthesized. Further, a carbon nanotube according to the presentinvention is hollow and can thus be filled with a material as desired bythe utilization of its capillary action.

Industrial Applicability

[0067] As will have been appreciated from the foregoing description, amethod of synthesizing highly oriented, aligned carbon nanotubes from anorganic liquid in accordance with the present invention allows carbonnanotubes aligned as highly (coaxially) oriented to be synthesized inbulk and at low cost. Also, the method of synthesis according to thepresent invention allows adaptation of a variety of existing Sitechnologies and is thus adapted for industrial mass production. Thepresent method requires neither vacuum nor any gaseous source materialand is thus suitable for industrial production. Further, it should be abasic technology for the synthesis of a variety of types of nanotubesand nanotube layer, especially an extremely important technology formaking hollow nanotubes and doped nanotubes.

[0068] Also, an apparatus according to the present invention forsynthesizing highly oriented, aligned carbon nanotubes from an organicliquid allows synthesizing carbon nanotubes in bulk, at low cost and insafety.

[0069] Further, highly oriented/aligned carbon nanotubes according tothe present invention can be synthesized in the form of a bundle ofcarbon nanotubes oriented, aligned highly coaxially, which when used ina variety of products brings about various excellent effects includingextremely high usability.

What is claimed is:
 1. A method of synthesizing highly oriented, alignedcarbon nanotubes from an organic liquid, characterized in that itcomprises the steps of: forming a substrate with a buildup thereon of athin film or fine insular particles composed of at least one metallicelement; exposing said substrate having said buildup to a hydrogenplasma; and heating said substrate exposed to the hydrogen plasma in anorganic liquid to a predetermined temperature whereby highly oriented,aligned carbon nanotubes are synthesized.
 2. A method of synthesizinghighly oriented, aligned carbon nanotubes from an organic liquid as setforth in claim 1, characterized in that said substrate is a Sisubstrate.
 3. A method of synthesizing highly oriented, aligned carbonnanotubes from organic liquid as set forth in claim 1, characterized inthat said at least one metallic element of which said buildup iscomposed is one or more elements selected from the group which consistsof Fe, Co and Ni.
 4. A method of synthesizing highly oriented, alignedcarbon nanotubes from an organic liquid as set forth in claim 1,characterized in that said organic liquid is alcohol.
 5. A method ofsynthesizing highly oriented, aligned carbon nanotubes from an organicliquid as set forth in claim 1, characterized in that said alcohol ismethanol or ethanol.
 6. A method of synthesizing highly oriented,aligned carbon nanotubes from an organic liquid as set forth in claim 1,characterized in that said step of heating to a predeterminedtemperature comprises heating by passing an electric current throughsaid Si substrate.
 7. An apparatus for synthesizing highly oriented,aligned carbon nanotubes, characterized in that it comprises: a liquidtank for retaining an organic liquid; a cooling means for cooling saidorganic liquid so as to maintain it at a temperature lower than aboiling point thereof; a condensing means for condensing said organicliquid becoming gaseous in phase into its original liquid phase forreturn into said liquid tank; a substrate holding means having anelectrode means for passing an electric current through said substratein said organic liquid; an inert gas inlet means for removing air fromsaid apparatus; and a tank sealing means for sealing said liquid tank toprevent said organic liquid becoming gaseous in phase from flying off.8. Highly oriented, aligned carbon nanotubes, characterized in that suchcarbon nanotubes are densely aligned on and firmly bonded to a Sisubstrate over, and oriented perpendicular to, an entire surfacethereof.
 9. Highly oriented, aligned carbon nanotubes, characterized inthat such carbon nanotubes are coaxially oriented, equal in length, andfastened together.